Retrievable through drill pipe formation fluid sampler



A. H. YOUMANS April 29, 1969 3,441,095

` RIIRIEVABLB THROUGH DRILL PIPE FORMATION FLUID SAMPLER Filed Nov. 28,1967 V c ww g M QQM United States Patent O 3,441,095 RETRIEVABLE THROUGHDRILL PIPE FORMATION FLUID SAMPLER Arthur H. Youmans, Houston, Tex.,assignor to Dresser Industries, Inc., Dallas, Tex., a corporation ofDelaware Filed Nov. 28, 1967, Ser. No. 686,206 Int. Cl. E21b 43/116,7/00; E21c I9/00 U.S. Cl. 175-59 9 Claims ABSTRACT OF THE DISCLOSUREBackground of the invention This invention relates to the retrieving offormation fluid samples during drilling operations and moreparticularly, it concerns retrievable fluid samplers of the type adaptedto be lowered through a tubular drill string to receive a sample of rockformation fluids at the bottom of a well bore and subsequently withdrawnfor an analysis of the fluids collected in the sampler, as well as amethod for retrieving such samples.

`Formation fluid samplers of the type to which the present inventionrelates have been widely used in the well drilling field rfor collectinga test sample of fluids present in subterranean formations penetrated bya drilling bit. Test samples collected in this manner are helpful inproviding information |which might lbe used, for example, to determinethe ultimate depth to which a well should be drilled for -bestproduction or easiest completion. v It is conventional practice yin welldrilling operations, to use a tubular drill string through whichdrilling mud is circulated downwardly and then upwardly in the annulusbetween the drill string and the well bore. The circulated drilling mud,therefore, serves to lubricate and cool the drilling bit as well as tocarry drilled particles upwardly out of the bore hole. The presence ofthe drilling mud at the bottom of the bore hole being drilled, however,poses problems in the collection of a formation fluid at the bottom ofthe hole. Specifically, any formation fluids thatl may be collected by awire line retrievable sampler in the tubular drill string will more thanlikely be contaminated by the drilling mud in situations whereconventional drill rigs are used. Such contamination of the sample makesit diliicult to analyze the sample after it has been retrieved andbrought to the surface.

Summary of the invention In accordance with the present invention, theproblems heretofore experienced with contamination of formation samplesby drilling mud are substantially overcome by employing a special drillcollar having an internal seat to complement the lower end of a uidsampler adapted to be lowered into and withdrawn fromthe tubular drillstring by a wire line or cable. The special drill collar also includesan expansible packer near its lower end which is inflated after thesampler is seated and thus expanded against the bore hole under thepressure of drilling mud within the drill string to block a centralorifice in the collar. A suitable perforator means is carried in thelower portion of the sampler including means to actuate it from thesurface. When actuated, the bottom of the bore hole is penetrated, orfractured, for a signifi- Mice cant distance ahead of the drill bit.Fluids in the undrilled formation immediately beneath the drill bit thenare able to move upwardly under formation pressure into the uid sampler.The packer serves to isolate the bottom of the bore hole so that theamount of drilling mud that might enter the sampler is insuflicient tocontaminate the sample collected by any significant amount.

Therefore, the objects of the present invention include: the provisionof a retrievable formation fluid sampler by which drilling mudcontamination of the formation uid is reduced to a minimum; theprovision of a fluid sampler arrangement which facilitates thecollection of a formation fluid sample originating from the formationpreceding the drill bit; the provision of a formation fluid sampler ofthe type referred to which is simple in construction and adaptable toexisting drilling equipment without extensive modification; and theprovision of a unique method for retrieving formation fluids from a wellbore during drilling operations.

Other objects and Ifurther scope of applicability of the presentinvention ywill become apparent from the detailed description to followtaken in conjunction with the accompanying drawings.

Brief description of the drawings FIG. l is a vertical cross-sectionthrough a Well bore and a drill collar adapted to receive the liuidsampler of this invention;

FIG. 2 is another vertical cross-section through the drill collar shownin FIG. l with the retrievable fluid sampler of this invention in place;and

FIG. 3 is a further vertical cross-section to illustrate the fluidsampler of this invention during the collection of a formation fluid.

Description of the preferred embodiment In FIG. 1 of the drawings, aconventional drill bit 10, having a centrally disposed mud circulationport 12 and a threaded shank 14, is shown mounted on the lower end of adrill collar, generally designated by the reference numeral 16, as itwould be arranged in operation on the lower end of a conventional drillstring 1S during the drilling of a well bore 20. Also in accordance withconventional drilling practice, drilling mud is circulated downwardlythrough the drill string 18 and through the drill collar 16 by surfaceequipment, including a pump 22, and then, upwardly in the annulusbetween the drill string 18 and the sides of the well bore 20 byappropriate apparatus, including a pump 24. The circulation of drillingmud through the drill string 18, the drill collar 16 and the port 12 inthe drill bit 10 is depicted by the arrows a in FIG. 1 of the drawings.

Also, as shown in FIG. 1 of the drawings, the drill collar 16 has aninwardly ared surface at its lower end defining a seat 26 concentricwith the port 12. The seat 26 is in tluid communication with the port 12in the drill bit, and the yfunction of the seat 26 will be described inmore detail presently.

The lower end of the drill collar 16 is circumscribed by an expansiblepacker 28 formed of elastomeric materials conventionally used for thispurpose and is secured to the drill collar 16 by clamping bands 30 atits upper and lower ends. The cylindrical wall of the drill collar 16 isprovided with an oriiice 32 located between the clamping bands 30 toenable drilling mud under pressure within the collar to act outwardlyagainst the packer 28 and to expand it outwardly against the well bore20.

It might also be mentioned at this point that the relative size of thesmaller orifice 32 and the larger port 12, together with the balance ofhydrostatic pressure across the walls of the drill collar 16, operate toprevent expansion of the packer 28 during normal drilling operations,the orifice 32 becoming effective when the port 12 is covered.

The fluid sampler of this invention is illustrated in two stages ofoperation in FIGS. 2 and 3 of the drawings and is designated generallyby the reference numeral 34. The fluid sampler 34 includes an elongatedcylindrical receptacle 36 to enclose a sample-receiving chamber 38. Theupper end of the receptacle 36 is closed and is formed with a threadedshank 40 to facilitate connection of the fluid sampler 34 to a wire lineor cable 42 by a suitable coupling 44.

A shoe 46, at the lower end of the receptacle 36, is shaped to form adownwardly converging curved seating surface 48, complementing the drillcollar seat 26. Because of the complementing, or matching,configurations of the Seating surfaces 26 and 48, the interior of thedrill collar 16 is isolated from the area of the drill bit 10, when thefluid sampler 34 is in the position shown in FIG. 2. The respectiveseating surfaces 26 and 48 may be formed, if desired, with a coating orother layer of resilient material to facilitate an even more effectiveseal. Y

As shown in FIGS. 2 and 3, a counterbore 50 is formed through the lowerend of the shoe 46 to form a chamber to receive a bullet 52 and anexplosive charge 54 behind the bullet 52. The bullet and charge areretained within the counterbore 50 by a displaceable pressure plug 56.An orifice 58 extends between the counter-bore 50 and the chamber 38 andis normally closed from communication with the chamber 38 by a valve 60.

In the disclosed embodiment, the valve 60V is retained in its closedposition Iby a helical seating spring 62 acting between the valve headand a bracket 64 secured on the inside of the receptacle 36. It iscontemplated, however, that the valve 60 may be of a type other thanthat disclosed in the drawings. For example, remotely controlled or timecontrolled valves may be used in place of the spring biased valve shown,thereby to enable positive control over the open and closed positions ofthe valve.

Also in the disclosed embodiment, an igniter 66 is connected by wires 67to the surface, for the purpose of igniting the explosive charge 54.Obviously, however, other forms of remote igniting means may be used,such as a wave form signal from the surface, or a suitable timingcircuit.

Further, it should be noted that whereas a bullet together with anassociated explosive charge is indicated as the preferred means forproducing the sampling bore 70, it is to be understood that a shapedcharge of the type used in oil well casing perforating may be employed.

In operation, when it is desired to take a sample of fluid from theformation in advance of the drill bit 10, the fluid sampler 34 islowered on the cable 42 into the position shown in FIG. 2 of thedrawings. Thereafter, the pump 22 or other suitable means is operated topressurize the drilling mud in the string 18 and drill collar 16.Because the port 12 is closed by the lower end of the shoe 46, thepressurized drilling mud will pass through the orifice 32 and expand thepacker 28 against the sides of the well bore 20, las shown in both FIGS.2 and 3 of the drawings. In this condition the area in the vicinity ofthe bit 10, is completely isolated or packed off from the remainder ofthe well bore 20.

After the packer 28 has been expanded against the well bore 20, theexplosive charge 54 is fired to project the bullet 52 downwardly throughthe orifice 12 and into the formation beneath the bit 10. The finalposition of the bullet 52 is depicted in FIG. 3 yat the lower end of arelatively small sampling bore 70. Fluids in the formation will migrateto the sampling bore 70 and under formation pressure, move upwardlythrough the now empty counterbore 50, through the orifice 58 against thehead of the valve 60. The pressure of the formation fluid will raise thevalve 60 causing the fluid to rise upwardly in the chamber 38. After apredetermined time, or when the pressure within the chamber 38 balancesthe pressure of the formation fluid, the valve 60 will seat to isolatethe chamber 38 from the well bore 20. The fluid sampler 34 then iswithdrawn to the surface for an analysis of the formation fluid sample.

In addition to obtaining la fluid sample for subsequent analysis, it isoften desirable also to determine the ambient fluid pressure in theformation from which the sample is taken. This may be accomplished bymeasuring the pressure in the chamber 38 after it has been removed fromthe borehole. Alternatively, it may be desired to observe the pressureduring the interval when chamber 38 is filling with the formation fluid.This may be accomplished by means of a pressure transducer 71 inside thechamber 38 and coupled by the necessary electrical conductors to surfaceindicating and recording means. The electrical conductors, not shown,may comprise conductors in the supporting cable 42, which may be aconventional logging cable. Conductors 67 which provide means fordetonating the explosive 54 may similarly be conductors of the cable 42.

Thus, an extremely effective retrievable formation fluid sampler isprovided by this invention and by which the above mentioned objectivesare completely fulfilled. Also, it is contemplated that various changesand/or modifications can be made in the apparatus shown and describedherein. Accordingly, it is expressly intended that the foregoingdescription is illustrative of a presently preferred embodiment only,not limiting, and that the true spirit and scope of the presentinvention is to be determined by reference to the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Apparatus for collecting formation fluid samples from a well boreduring drilling operations, said apparatus comprising:

a tubular drill collar adapted to be connected at its upper end to atubular drill string and to support an apertured drill bit at its lowerend,

said drill collar being open at its lower end and having an inwardlyfacing seating surface formed there- 1n,

an expansible packer mounted exteriorly about the lower end of saiddrill collar,

means to expand said packer outwardly against the wall of the well bore,and

a fluid sampler adapted to be lowered into said drill collar, saidsampler comprising:

means defining a fluid receiving chamber having upper and lower ends,

said lower end having an exterior seating surface to engage the inwardlyfacing seating surface in said collar to plug the lower open end of saidcollar,

means defining a passageway extending through said lower end of saidchamber,

valve means operable to close off said chamber from said passageway,

means to support a perforating means in said lower end of said chamber,and

means to actuate said perforating means, whereby the formation precedingthe drill bit may be penetrated to release fluids therein for flowupwardly into said chamber.

2. The apparatus recited in claim 1 wherein said means to expand saidpacker outwardly includes an orifice in the wall of said collar oversaid outwardly facing seating surface whereby said packer may beexpanded by fluid pressure on the inside of said collar after saidsampler plugs the lower end thereof.

3. The apparatus recited in claim 1 wherein said perforating meansincludes a bullet and a propelling charge within a counterbore extendinga predetermined distance from the lower end of said passageway wherebysaid passageway is initially blocked by the bullet and the charge butopened upon ignition of said charge and projection of said bulletdownwardly into the formation preceding the bit.

4. The apparatus recited in claim 1 including means for connecting aretrieving line to the upper end of said chamber defining means.

5. A formation fluid sampler for use with a tubular drill string havinga drill collar at its lower end to carry a drill bit having a centralaperture establishing a circulation path for drilling mud passed downthrough the drill string and u-p through the yannulus between the drillstring and the well bore being drilled, the drill collar having also anexpansible packer mounted exteriorly about its lower end and an orificecommunicating with the interior of the packer for expansion thereof bypressurized uid in the drill string, said sampler comprising:

a receptacle means to provide a sample receiving chamber; means on theupper end of said receptacle to connect a retrieving line;

an exterior seating surface on the lower end of said receptacleco-operable with the drill collar and bit to plug the drilling mudcirculation path provided therein,

means to define a passageway extending from the lower end of saidreceptacle to said chamber;

valve means movable between yan open position and a closed positionblocking communication of said passageway with :said chamber;

means to support a bullet and a propelling charge in said lower end ofsaid receptacle; and

means to ignite said charge.

6. The apparatus recited in claim 5 in which said passageway includes arestricted portion opening to said chamber at its upper end *and acounterbore between the lower end and said restricted portion.

7. The apparatus recited in claim 6 in which said bullet and chargesupporting means comprises an expansive plug in the lower end of saidcounterbore, the bullet and c'h-arge being located initially in saidcounterbore.

8. The method of retrieving a formation iluid sample from the bottom ofa well bore during drilling operations of the ty-pe in which drillingmud is circulated throughy a tubular drill .string and a drill bitcarried on the lower end thereof, said method comprising the steps oflowering a sample collecting receptacle into the tubular drill stringand isolating the interior of the drill string from the bit, packing offthe annulus between the drill string and the well bore at the lower endof the well bore to isolate the bit from the remainder of the bore,

propelling a perforating means into the formation p-receding the bit torelease iluids for collection in said receptacle, iand withdrawing thereceptacle and the iluid sample therein from said tubular drill string.

9. The method recited in claim 8 wherein the lower end of the well boreis packed off by pressurizing the interior of the tubular drill stringto expand an expansible packer against the well bore.

References Cited UNITED STATES PATENTS 1,560,815 11/1925 Hill 175-4.52 X2,265,982 12/1941 Bolton 175-4.58 X 2,544,573 3/1951 Vincent 175-4.59 X2,923,204 2/ 1960 Mohaupt 175-4.58 X 3,115,932 12/1963 Reynolds175--4.52 3,394,767 7/1968 Terry 175-4.52 3,032,108 5/ 1962 Bielstein175-4.52

NILE C. BYERS, JR., Primary Examiner.

U.S. C1. XJR.

